Chin strap



FIG. 1 is a left front perspective view of a chin strap showing the new invention with one of the attachment straps pulled away;

FIG. 2 is a right back side perspective view thereof; and,

FIG. 3 is a left front perspective view thereof.

The broken line showing of human head is included for the purpose of illustrating environmental structure and forms no part of the claimed design. 

I claim the ornamental design for a chin strap, as shown and described. 